Thermostat



NOV- 29, 1955 J. T. BAKER Erm. 2,725,443

THERMOSTAT Filed July 25, 1954 lja :NSuLAnoN 1% 30 J6 J6. Inllgnnau H W l V511 ya; cjyl Ewig/Swami@ ATTO/Q/VEYJ United States Patent O THERMOSTAT John T. Baker and Cary H. Marshall, Middlebury, Vt. Application July 23, 1954, Serial No. 445,265

3-Claims. (Cl. 20G-137) The present invention relates generally to controls and specifically to a thermostaticallyactuated switch.

The principal object of the present invention is to provide a compact control device having a very sensitive and easily-operated adjustment.

Another object of the present invention is to provide an inexpensively constructed and assembled thermostatically-actuated switch which can be incorporated in a re alarm system, and one which may be mounted on slightly irregular surfaces without special brackets.

A further object of the present invention is to provide a thermostatic tire alarm which can be adjusted to close a circuit at any degree of temperature within a range of temperatures known to be in the vicinity of combusting materials.

These and other objects and advantages of the present invention will be readily apparent from the following description when considered in connection with the annexed drawings, in which:

Figure 1 is a top plan view of the present invention,

Figure 2 is a side view in elevation and partially in cross section as seen on line 2 2 of Figure l,

Figure 3 is a bottom plan view showing the connectors,

Figure 4 is an end view in section on line 44 of Figure 1,

Figure 5 is an end View in section on line 5--5 of Figure l,

Figure 6 is an end View in section on line 6-6 of Figure 1,

Figure 7 is a view in cross section of a second embodiment of one portion of the invention,

Figure 8 is a View in cross section of a third embodiment, and

Figure 9 is a schematic view of the invention in a lire alarm circuit.

Referring in more detail to the drawings, in which like reference numerals indicate like parts throughout the several views, it will be seen that the present invention consists of an elongated base 10 formed of a somewhat flattened channel strip to provide a recess 11 on its underside. At one end 12 of the base 10 is secured an upstanding insulating block 13 provided in one end with a recess 14. At the other end of the base 10 is a second insulating block 15 provided with a bore 16 substantially in alignment with the recess 14.

Each of the blocks 13 and 15 are secured to the base 10 by bolts 17, and the block 13 has one end of an elongated thermostat bar 18 received in its recess 14 and secured therein by the bolt 19 which is threaded into a hole 21 in the bar 18, the bolt 19 extending through suitable insulation and the base 10 and forming an electrical contact for the short connector bar 22.

The other end of the bar 18 is slidable in the one end of the bore 16 and ends in a contact face 23, the contact face being received in a conducting bushing 24 in the bore 16. The bushing 24 has a threaded hole 25 to receive the contact screw 26, one end of which is ice 2 pointed to form a contact point 27 adjacent the contact face 23.

It will be seen therefore that the bar 18 itself is a part of the electrical circuit and by its expansion under the application of heat, the contact face 23 moves in the bore 16 to make electrical contact with the point Z7, completing a circuit which includes the bolt 28 and a second connector bar 29, seen in Figure 3.

In order that the bar 18 be a good conductor of electrical current it is therefore of substantial area in circular cross section, and in order that it be quickly responsive to any change in temperature, the iins 3i) are provided, each one of which is secured to the bar in a maximum heat-transfer condition of welding, brazing or by electro-chemical plating means which coats both the bar 18 and the tins with a continuous molecular structure known to have excellent heat transfer properties. Although the fins are shown as circular in shape, it is not important that they be of any particular shape, and may occupy all of the area above the base 1@ as is deemed to be suitable.

In the second embodiment shown in Figure 7, a spring clip 31 is secured to the end of the bar 18 by means of a bolt 32 screwed into a threaded recess 33 in the bar. This spring clip 31 insures a good electrical contact screw 26a on which the point 27 is omitted.

ln the third embodiment shown in Figure 8, the recess 34 in the bar 13 need not be threaded but has pressiitted into it one end of the compression spring 35 which makes contact at its other end with the contact screw 26b.

In each of the second and third embodiments it will be seen that further expansion after contact is made will not bend or damage the rod 18.

The operation of the invention is believed to be obvious, in Figure 9, three of the devices are in a circuit in parallel, any one of them being able to close the circuit to actuate an alarm or sprinkler system. The base 10 is purposely constructed with rubber grommets .36 around the mounting holes 37 so that the base can be mounted on slightly irregular surfaces, such as ceilings, beams, window sills and other places commonly used for ire detection devices.

While only preferred forms and preferred embodiments have been described and illustrated herein, many other embodiments are contemplated and many changes and modifications may be made without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

l. A thermostatically-actuated switch comprising an elongated base, an insulating block secured one at each end of said base, said blocks being arranged in longitudinal confronting end to end alignment, one of said blocks being provided with a recess extending inwardly of the confronting end and the other being provided with an axially extending bore aligned with said recess, an elongated bar expansible in response to temperature increase xedly secured at one end in said recess and movably secured by its other end'in said bore, electrical Contact means extending through said base connected to said one end, said bar being provided at its other end with a contact face and said other block being provided with a contact point in said bore, and electrical connection means connecting said point with a connector mounted on said base, said face 'and said point being adapted to close an electrical circuit including said bar, said connector and said contact means.

2. A thermostatically-actuated switch comprising an elongated base, an insulating block secured one at each end of said base, said blocks being arranged in longitudinal confronting end to end alignment, one of said blocks being provided with a recess extending inwardly of the confronting end and the other being provided with an axially extending bore aligned with said recess, an elongated bar expansible in response to temperature increase xedly secured at one end in said recess and movably secured by its other end in said bore, electrical contact means extending through said base connected to said one end, said bar being provided at its other end with a spring clip and said other block being provided with a contact screw in said bore, and electrical .connection means connecting said screw with a connector mounted on said base, said spring clip and said contact screw being adapted to close an electrical circuit including said bar, said connector and said Contact means.

3. A thermostatically-actuated switch comprising an elongated base, an insulating block secured one at each end of said base, said blocks being arranged in longitudinal confronting end to end alignment, one of said blocks being provided with a recess extending inwardly of the confronting end and the other being provided with an axially extending bore aligned with said recess, an elongated bar expansible in response to temperature increase xedly secured at one end in said recess and movably secured by its other end in said bore, electrical contact means extending through said hase connected to said one end, said bar being provided at its other end with a compression spring and said other block being provided with a contact screw in said bore, and electrical connection means connecting said contact screw with a connector mounted on said base, said compression spring and said Contact screw being adapted to close an electrical circuit including said bar, said connector and said contact means.

References Cited in the ile of this patent UNITED STATES PATENTS 671,236 Renault Apr. 2, 1901 1,000,661 Beers et al Aug. 15, 1911 1,111,652 Frylng Sept. 22, 1914 1,891,507 Stanbon Dec. 20, 1932 

